大页内存huge_page

# 标准大页和透明大页

https://blog.csdn.net/cpongo3/article/details/88798139 (opens new window)

大页内存分为标准大页和透明大页

# 标准大页

https://blog.csdn.net/crazycoder8848/article/details/44983265 (opens new window)

# 查看系统保留的大页内存数量

cat /proc/sys/vm/nr_hugepages

# 设置大页内存数量为192

echo 192 > /proc/sys/vm/nr_hugepages

# 使能透明大页

参考tcmalloc调优文档: https://google.github.io/tcmalloc/tuning.html#system-level-optimizations (opens new window)

/sys/kernel/mm/transparent_hugepage/enabled:
    [always] madvise never

/sys/kernel/mm/transparent_hugepage/defrag:
    always defer [defer+madvise] madvise never`

/sys/kernel/mm/transparent_hugepage/khugepaged/max_ptes_none:
    511

/proc/sys/vm/overcommit_memory:
    1

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配置

echo always >  /sys/kernel/mm/transparent_hugepage/enabled

echo 1 > /proc/sys/vm/overcommit_memory:

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# 查看大页使用情况

cat /proc/meminfo | grep -i huge

# 查看某个进程的大页使用情况

cat /proc/pid/smaps | grep -i huge

# mount hugetlbfs

mkdir -p huge_pages
mount -t hugetlbfs none huge_pages -o pagesize=2048K

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# 相关项目

libhugetlbfs hugectl

# 代码

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <errno.h>
#include <sys/mman.h>
#include <stdlib.h>
#include <unistd.h>

#define    ERR_DBG_PRINT(fmt, args...) \
    do \
    { \
        printf("ERR_DBG:%s(%d)-%s:\n"fmt": %s\n", __FILE__,__LINE__,__FUNCTION__,##args, strerror(errno)); \
    } while (0)
 
 
/* mmap方式可以使用指定尺寸的巨页池 */
int main(int argc, char *argv[])
{
    const char *fname = "huge_pages/page1.txt";
    int ret = system("mkdir -p huge_pages");
    ret = system("mount -t hugetlbfs none huge_pages -o pagesize=2048K");

    int fd = open(fname, O_CREAT | O_RDWR, 0755);
    // char *huge_mem = (char *)mmap(NULL, 2048*1024*5, (PROT_READ | PROT_WRITE), MAP_SHARED, fd, 0); 

    // fix addr.
    char *huge_mem = (char *)mmap((void *)0x7ff000000000, 2048*1024*5, (PROT_READ | PROT_WRITE | PROT_EXEC), 
        MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB, fd, 0);


    if (ret<0)
    {
        ERR_DBG_PRINT("mount fail:");
        return 0;
    }
 
    if (fd<0)
    {
        ERR_DBG_PRINT("open fail:");
        return 0;
    }
 
    if (-1 == (int)(unsigned long)huge_mem)
    {
        ERR_DBG_PRINT("mmap fail:");
        return 0;
    }
 
    printf("press any key to access huge page\n");
    getchar();
 
 
    memset(huge_mem, 0, 2048*1024*5);
 
    printf("press any key to delete huge page\n");
    getchar();
 
    /* 下面代码一执行，内存就释放回巨页池了 */
    if (unlink(fname)==-1)
        ERR_DBG_PRINT("unlink fail:");
 
    return 0;
}

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# 内核中mmap关于 MAP_HUGETLB 的合法性校验

https://stackoverflow.com/questions/70386773/how-to-implement-map-hugetlb-in-a-character-device-driver

MAP_ANONYMOUS 表明该 The mapping is not backed by any file; its contents are initialized to zero.

对于mmap，当指定了MAP_HUGETLB时，要么是MAP_ANONYMOUS，要么是该文件被mount在hugetlbfs上

    if (!(flags & MAP_ANONYMOUS)) { // <== File-backed mapping?
        audit_mmap_fd(fd, flags);
        file = fget(fd);
        if (!file)
            return -EBADF;
        if (is_file_hugepages(file)) { // <== Check that FS is hugetlbfs
            len = ALIGN(len, huge_page_size(hstate_file(file)));
        } else if (unlikely(flags & MAP_HUGETLB)) { // <== If not, MAP_HUGETLB isn't allowed
            retval = -EINVAL;
            goto out_fput;
        }
    } else if (flags & MAP_HUGETLB) { // <== Anonymous MAP_HUGETLB mapping?

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# 透明大页THP Transparent Huge Page

pass

编辑

上次更新: 2023/05/07, 17:27:54

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